The application relates to an integrated circuit device with a semiconductor body and to a method for the production of an integrated circuit device. The semiconductor body includes a cell field with a drift zone of a first conduction type. In addition, the semiconductor device includes an edge region surrounding the cell field. Field plates with a trench gate structure are arranged in the cell field.
In semiconductor devices with field plate compensation structures, the cell field is surrounded by an edge region for which an edge termination has to be provided. For this purpose, the active region, which is initially completely free of a field oxide, is defined as a cell field. In the cell field, the field plates in the trench structure are surrounded by a field plate insulation. The outer trenches or field plates of the cell field are provided with a field plate insulation which is brought out to a field oxide on the front side of the semiconductor body in the edge region.
In addition, a continuous trench, a edge trench, surrounds the entire cell field, its clearance generally corresponding to the spacing of the trench structures in the cell region.
Such a structure of a semiconductor device is subject to two types of problems. First, the edge trench is subjected to the highest loading, as compensation is no longer complete on the side of the edge trench remote from the cell field. As a result, a breakdown may occur at the continuous edge trench, the location of the breakdown being the curvature at the trench base adjacent to the cell field. There is therefore a risk that this edge breakdown may occur earlier than the cell field breakdown, so that the blocking capability of the edge trench has to be increased. A further problem is found in the region of the source fingers with conductive contact material, as these contacts are only provided outside the active cell field, leaving a certain minimum distance between the end of the body zones and the continuous edge trench.
In the region of the edge trench, the potential can directly reach the field oxide from below in the semiconductor body, which could cause problems. In principle, doping must not exceed a critical value, otherwise a potential breakdown at the trench base could jump upwards to a trench contact, whereby breakdown voltage is significantly reduced. A reduction of the concentration of doping material towards the surface, which is possible in an epitaxial process, slightly reduces the ability of the potential to reach the field oxide while reducing the load on the continuous edge trench. The reduction of the concentration of doping material, however, adversely affects on resistance.
For these and other reasons, there is a need for the present invention.